1. Field of the Invention
This invention relates to an automatic shut-off type fuel dispensing nozzle with an automatic valve closing mechanism which is adapted to close a valve automatically when a liquid in a container, which is being replenished, reaches a predetermined level.
2. Description of the Prior Art
Generally, the automatic shut-off fuel dispensing nozzles of this sort incorporate, in the vicinity of a fuel inlet end of a nozzle body, a hook which is provided with a plural number of grooves to serve as means for holding an operating lever in a valve open position at the time of an automatic shut-off fuel dispensing operation, in which the operating lever is pulled about a pivotal point at its pivotal connection to a plunger thereby pushing up a valve stem to open the valve and engaging an end portion of the operating lever with a groove of the hook. However, the fuel dispensing nozzles of this type have a drawback that, due to a large distance between the pivoting point of the operating lever and its hook engaging position, the operating lever is easily disengaged from the hook even when slight vibration is applied to the nozzle body or operating lever, automatically closing the valve before the liquid in the container reaches the predetermined level.
In order to eliminate the above-mentioned drawback, there have thus far been proposed various automatic shut-off nozzles including, for example, Japanese Patent Publication No. 49-12218 which discloses an arrangement including, as means for retaining the operating lever in valve open position, a lower lever pivotally supported for movement about a first pivotal point at a connection to a plunger to push up a valve stem, an upper lever having one end thereof pivotally supported for movement about a second pivotal point at the other end of the lower lever, with a valve stem passed therethrough by way of a guide plate or guide rollers, and forming a handle for operating the other end, a trigger pivotally supported for movement about the second pivotal point for maintaining the valve open position, and a rack mounted on a lever guard for holding the fore end of the trigger, the lower and upper levers constituting an operating lever.
At the time of the valve opening operation, the lower and upper levers are turned about the first pivotal point and the trigger is engaged with the rack to maintain the valve open position. As soon as the liquid in the container reaches a predetermined level, a diaphragm is moved to release the plunger from engagement with latch means consisting of a latch pin and balls, opening the valve body and pushing the valve stem by a valve spring thereby to cause the lower lever alone to turn counterclockwise about the second pivotal point and to disengage the trigger from the rack.
With the above-described prior art nozzle construction, the trigger is engaged with the rack on the lever guard in such a manner that the trigger is stuck against a notch or a stepped portion of the rack, holding the valve stem securely in the valve open position. For closing the valve, the lower lever is turned counterclockwise through the valve stem by the action of a valve spring which urges a valve body in a valve closing direction. In association with this operation, the trigger is released in a secure and reliable manner.
However, the above-described prior art construction has a number of drawbacks as follows.
(1) The operating lever which consists of lower and upper levers is adapted to retain the valve open position by abuttingly engaging the trigger against a notch or stepped portion of the rack, ensuring secure engagement with the rack. However, since the rack is fixedly secured on the inner surface of the lever guard and the fore end of the trigger is forcibly held in frictional engagement with a notch or stepped portion of the rack, there sometimes occurs a trouble that the trigger fails to disengage from the rack even after the lower lever is turned counterclockwise about the second pivotal point due to the replenished liquid in a fuel tank reaching a predetermined level.
(2) The operating lever is basically constituted by two members, namely, a lower lever and an upper lever which is pivotally supported by the lower lever, so that it requires an increased number of parts including a connecting pin and a rivet, lowering the efficiency of machining and assembling operations.
(3) The rack which is formed with notches or steps is fixedly mounted on the inner surface of the lever guard. That is to say, it is necessary to provide a rack separately and mount it on the lever guard by the use of rivets. This arrangement similarly lowers the efficiency in machining and assembling operations.
(4) The valve stem is passed through the upper lever in contact with a guide plate or guide rollers which are provided on the upper lever, and abuttingly engageable with the bottom surface of a channel on the lower lever to push and turn the lower lever about the second pivotal point. Therefore, it is necessary to provide on the upper lever a guide plate which slidably receives the valve stem or a pair of guide rollers which grippingly guide the valve stem, inviting a further increase in the number of parts in addition to the abovementioned drawbacks.